21-CT-55 has a new home

[miniman82]

Wow, outstanding work!

Looks like they are pretty close, for the most part. I'd bet the later tubes are farther apart than the early ones, have you tested any of them?

[cbenham]

Originally Posted by miniman82

Wow, outstanding work!

Looks like they are pretty close, for the most part. I'd bet the later tubes are farther apart than the early ones, have you tested any of them?

Here are the spectrum charts for the 15GP22 and a rare earth Mitsubishi tube at the ETF Museum. Please note that the vertical scale for the 15GP22 is different than that of the 21AXP22 and the rare earth tube. That's why it appears to be very low when in fact it is close to the 21AXP22.

[old_tv_nut]

Originally Posted by cbenham

Here are the spectrum charts for the 15GP22 and a rare earth Mitsubishi tube at the ETF Museum. Please note that the vertical scale for the 15GP22 is different than that of the 21AXP22 and the rare earth tube. That's why it appears to be very low when in fact it is close to the 21AXP22.

The spectrum from the Eye-one has 10 nm resolution, which is good enough for color calculations, but does not show how spiky the rare earth red is.

This page has a finer resolution plot of the individual phosphors in a modern tube, about 20% down the page:
http://www.websters-online-dictionar...&sa=Search#922

[old_tv_nut]

Originally Posted by miniman82

Wow, outstanding work!

Looks like they are pretty close, for the most part. I'd bet the later tubes are farther apart than the early ones, have you tested any of them?

The 1931 CIE chart shown exaggerates the difference in green and minimizes it in blue. The difference between the CBS blue and others is as significant as the difference in green between the SMPTE and others. There is an alternate plot developed in 1976 that is closer to uniform variation.

Here are the two versions of the plot (1931, x,y; 1976 u',v') comparing several color gamuts:


Technicolor at three different dye concentrations
(Many thanks to Ed Reitan for supplying the dye spectral curves used to calculate these colors);

NTSC;
sRGB (digital still cameras and HDTV);
Fujichrome test target;
Kodachrome test target;
Pointer's surface colors (a survey of the range of natural, paint, and printed colors).

Note the more significant differences in the blue and magenta region shown on the u', v' diagram.